This is rundown of the stock coolers for the Intel i5 and AMD Phenom II processors that I have along with third party coolers.
Update: I was not entirely happy with the stock HSF for PII 965. It is adequate at the stock speed of 3.4 Ghz and probably 3.6 Ghz. However, it does tend to blow hot air on both the motherboard chipset and the memory. And, with my particular case arrangement I have a large, 200mm fan right above the cooler that draws upward. However, because the fins run left and right this is no benefit.
Update: The Freezer 64 seems much better. I was very concerned that the fan would not clear the DIMMs on the right side of the cpu socket. You can see this in the above picture. The problem with this is that it would have required me to turn the cooler around and then the fan would be blowing backwards. However, it does indeed clear the DIMMs.
Most people wouldn't have the very large fan right above the cooler; but you can see that even with the boxing effect of the video card, the air is directed properly toward the rear case fan. This is much better than the stock fan since it draws cooling air across the DIMMs and then blows cooling air across the chipset heatsinks behind the CPU socket. The air coming from this heatsink is much cooler than it was from the stock heatsink, presumably because of the increased airflow from the larger fan. There may also be some benefit from the vertical draw from the large fan since the fins are aligned vertically.
I'm current running my PII X4 965 at 3.8 Ghz with the NB at 2.6 Ghz. This seems pretty stable. I've been able to pass OCCT Linpack at about 60 C at 3.9 Ghz. I'm a bit disappointed that I couldn't get the NB up to 2.8 Ghz. I'm not sure how much of this is due to the BIOS. The version I'm using is the very first version that works with this processor.
My opinion so far is that if you have an X3 720 there is very little reason to replace the stock cooler, however I like the Freezer 64 much better than the stock cooler on the PII 965. The Freezer 64 matches the normal weight allowance of 500 grams and since it uses the same cam latch, it installs just like the stock unit. The extra airflow means that the exhaust air is much cooler and this is something I greatly prefer for the motherboard.